1. Field of the Invention
The present invention relates to a glass run.
2. Related Art
In general, a glass run is provided along a circumferential end of a glass opening of a motor vehicle. The glass run is provided with extruded portions which are extruded substantially in straight line (or in an elongated fashion) and molded portions which each connect the extruded portions together in such a state that the extruded portions are connected together at a predetermined angle and includes, for example, a front vertical section, a top section and a rear vertical section so as to follow the shape of the glass opening. In addition, when viewed in a cross-sectional direction, the glass run has a main body which is provided with a base portion, and an interior side wall portion and an exterior side wall portion which extend from the base portion to thereby be formed substantially into a U-shape in cross section, an interior seal lip and an exterior seal lip, the interior seal lip and the exterior seal lip extending into an inner space of the main body from substantially distal ends of both the side wall portions, respectively. In the glass run, the main body is mounted on an inner part of a mounting frame (or a channel portion) which is provided to extend along the glass opening, whereby the door glass is sealed by the pair of seal lips on an internal side and an external side thereof.
In addition, as materials for forming the glass run, ethylene-α-olefin non-conjugated diene copolymer (EPDM), olefin-based thermoplastic elastomer (TPO) and the like are known.
Incidentally, there occurs from time to time a case where in sliding up and down, a door glass gets loosened or rattles when it is caused to vibrate in a transverse direction of a vehicle. To cope with this problem, conventionally, there has been proposed a technique in which a solid piece, a sponge member or the like is affixed to a predetermined part on an inner surface of the interior side wall portion of the glass run so as to support the interior seal lip which is deflected towards the inside of the vehicle when it is pushed by the door glass. In this case, although the looseness of the door glass is suppressed, since the solid piece or the sponge member needs to be affixed separately, there may be caused a fear that a reduction in working efficiency in manufacturing glass runs and an increase in production cost thereof are called for.
To cope with this problem, there has been proposed another technique in which a sub-lip is provided on the interior side wall portion so as to extend therefrom on the side of the inner space of the main body, so that the sub-lip is made to be brought into contact with an opposite surface (a back surface) of the interior seal lip to a glass contact surface thereof when the door glass is displaced largely towards the inside of the vehicle, so as to suppress the looseness of the door glass (for example, refer to JP-A-2000-33822).
Since the sub-lip and the interior side wall portion can be formed simultaneously by adopting the configuration described in JP-A-2000-33822, the reduction in working efficiency in manufacturing glass runs and increase in production costs thereof can be prevented. In the technique described in JP-A-2000-33822, however, it is not until the door glass is largely displaced towards the inside of the vehicle and as a result, the interior seal lip is largely deflected towards the inside of the vehicle that the interior seal lip is brought into contact with the sub-lip. Namely, the displacement of the door glass towards the inside of the vehicle is still suppressed or absorbed only by the internal seal slip until the interior seal lip is brought into contact with the sub-lip.
Moreover, the part of the back surface of the interior seal lip which is brought into contact with the sub-lip (or the distal end portion of the sub-lip) is set on a root portion side of the interior seal lip, and hence, the sub-lip of JP-A-2000-33822 was not such as to give an effective reaction force to the interior seal lip so as to allow the interior seal lip to return to its normal position.
Because of this, for example, in the event that the interior seal lip wears as a result of sliding contact with the door glass, whereby the elastic force (or the reaction force attempting to push back the door glass) is weakened, once it is pushed by the door glass, the interior seal lip deflects relatively easily towards the inside of the vehicle until it comes into contact with the sub-lip. Because of this, not only the effect to suppress the looseness of the door glass is reduced but also there is caused a concern that the sealing properties are decreased.